Method and device for resource configuration in handover

ABSTRACT

A technique relating to resource configuration in a wireless communication network. A terminal device in the wireless communication network receives information about supplemental resource from a source cell. Then the terminal device determines a time interval, in which the supplemental resource is available to the terminal device, in a transition period of a handover from the source cell to a target cell based on a timer associated with a random access procedure in the handover. In this way, the terminal device may use the supplemental resource during the handover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/511,180, filed Mar. 14, 2017, which is a National stage ofInternational Application No. PCT/CN2017/074509, filed Feb. 23, 2017,which claims priority to International Application No.PCT/CN2016/078389, filed Apr. 1, 2016, which are all hereby incorporatedby reference.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field ofcommunications, and more particularly, to a method and device forresource scheduling in handover (HO).

BACKGROUND

Wireless communication systems are advancing to provide good servicequality, support a high data rate and keep up with the continuouslyincreasing demand for wireless data traffic. The wireless communicationsystems, such as a Long Term Evolution (LTE) system, have been extendedwith support of device to device (D2D) features targeting bothcommercial and Public Safety applications. Some applications enabled byLTE are device discovery, where devices are able to sense the proximityof another device and associated application by broadcasting anddetecting discovery messages that carry device and applicationidentities. Another application consists of direct communication basedon physical channels terminated directly between devices. In 3GPP, allof these applications are defined under the umbrella of ProximityServices (ProSe).

One of the potential extensions of the ProSe framework consists ofsupport of V2X communication, which includes any combination of directcommunication between vehicles, pedestrians and infrastructure. The V2Xcommunication may include V2V communication, V2P communication, V2Icommunication, and the like. In particular, the V2V is also referred toas vehicle-to-vehicle, which covers LTE-based communication betweenvehicles, the V2P is also referred to as vehicle-to-pedestrian, whichcovers LTE-based communication between a vehicle and a device carried byan individual (e.g. handheld terminal carried by a pedestrian, cyclist,driver or passenger), and the V2I is also referred to asvehicle-to-infrastructure which covers LTE-based communication between avehicle and a roadside unit/network. V2X communication may takeadvantage of a NW infrastructure, when available, but at least basic V2Xconnectivity should be possible even in case of lack of coverage.Providing an LTE-based V2X interface may be economically advantageousbecause of the LTE economies of scale and it may enable tighterintegration between communications with the V2I, V2P and V2Vcommunications.

From V2X perspective, a handover procedure of a terminal device mayinclude a detach phase in which the terminal device detaches from itssource cell and has not been connected to its target cell, and anabnormal phase in which the terminal device is connected to the targetcell, but cannot use the resource in the target cell for V2Xtransmission. During the detach phase, the terminal device can neitherobtain resource from the source cell nor the target cell for V2Xtransmission. At the same time, the terminal device is under networkcoverage, it cannot use pre-configured resources as a UE out of coveragecan use. As a result, there will be service interruption during thisphase, and the interruption time can be up to, for example, 2 seconds,which will be unacceptable for some V2X services.

SUMMARY

In general, embodiments of the present disclosure provide a solution forresource configuration in a wireless communication network.

In a first aspect, a method at least partially implemented by a terminaldevice in a wireless communication network is provided. The terminaldevice receives information about supplemental resource from a sourcecell. Then the terminal device determines a time interval, in which thesupplemental resource is available to the terminal device, in atransition period of a handover from the source cell to a target cellbased on a timer associated with a random access procedure in thehandover. The corresponding computer program is also provided.

In one embodiment, determining the time interval may include:determining a time point when the timer is started as a beginning of thetime interval; and determining an end of the time interval based on astate of the timer.

In one embodiment, determining the end of the time interval may include:in response to the timer being stopped before expiring, determining atime point when the timer is stopped as the end of the time interval.

In one embodiment, determining the end of the time interval may include:in response to the timer being stopped before expiring, determining atime point when Radio Resource Control (RRC) connection reconfigurationis received as the end of the time interval.

In one embodiment, determining the end of the time interval may include:in response to the timer expiring, determining a time point when thetimer expires as the end of the time interval.

In one embodiment, determining the end of the time interval may include:in response to the timer expiring, determining a time point when afurther timer associated with a cell selection procedure is stopped orexpires as the end of the time interval, the cell selection procedurebeing performed after the random access procedure.

In one embodiment, the method may further include: adjusting the timeraccording to at least one of: Global Navigation Satellite System (GNSS)timing, and common timing of the wireless communication network.

In one embodiment, determining the time interval may include: inresponse to the timer being stopped before expiring, determining a timepoint when the timer is stopped as a beginning of the time interval; anddetermining a time point when RRC connection reconfiguration is receivedas an end of the time interval.

In one embodiment, the method may further include: adjusting the timeraccording to at least one of: GNSS timing, common timing of the wirelesscommunication network and timing of the target cell.

In a second aspect, a method at least partially implemented by a networkdevice in a wireless communication network is provided. The networkdevice transmits information about supplemental resource to a terminaldevice, to enable the terminal device to determine, based on a timerassociated with a random access procedure in a handover of the terminaldevice, a time interval in a transition period of the handover. Thesupplemental resource is available to the terminal device in thedetermined time interval. The corresponding computer program is alsoprovided.

In a third aspect, an apparatus at least partially implemented at aterminal device in a wireless communication network is provided. Theapparatus includes a receiver and a controller. The receiver isconfigured to receive information about supplemental resource from asource cell. The controller is configured to determine, based on a timerassociated with a random access procedure in a handover from the sourcecell to a target cell, a time interval in a transition period of thehandover, the supplemental resource being available to the terminaldevice in the determined time interval.

In a fourth aspect, an apparatus at least partially implemented at anetwork device in a wireless communication network is provided. Thenetwork device includes a transmitter. The transmitter is configured totransmit information about supplemental resource to a terminal device,to enable the terminal device to determine, based on a timer associatedwith a random access procedure in a handover of the terminal device, atime interval in a transition period of the handover, the supplementalresource being available to the terminal device in the determined timeinterval.

In a fifth aspect, a device is provided. The device includes: aprocessor and a memory, the memory containing instructions executable bythe processor, whereby the processor being adapted to cause the deviceto: receive information about supplemental resource from a source cell;and determine, based on a timer associated with a random accessprocedure in a handover from the source cell to a target cell, a timeinterval in a transition period of the handover, the supplementalresource being available to the terminal device in the determined timeinterval.

In a sixth aspect, a device is provided. The device includes: aprocessor and a memory, the memory containing instructions executable bythe processor, whereby the processor being adapted to cause the terminaldevice to: transmit information about supplemental resource to aterminal device, to enable the terminal device to determine, based on atimer associated with a random access procedure in a handover of theterminal device, a time interval in a transition period of the handover,the supplemental resource being available to the terminal device in thedetermined time interval.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of variousembodiments of the disclosure will become more fully apparent, by way ofexample, from the following detailed description with reference to theaccompanying drawings, in which like reference numerals or letters areused to designate like or equivalent elements. The drawings areillustrated for facilitating better understanding of the embodiments ofthe disclosure and not necessarily drawn to scale, in which:

FIG. 1 shows an environment of a wireless communication network 100 inwhich embodiments of the present disclosure may be implemented;

FIG. 2 shows a diagram of flow 200 of a handover procedure;

FIG. 3 shows a flowchart of a method 300 for resource configurationimplemented by a terminal device in accordance with an embodiment of thepresent disclosure;

FIG. 4 shows a flowchart of a method 400 for resource configurationimplemented by a network device in accordance with an embodiment of thepresent disclosure;

FIG. 5 shows a diagram 500 of a successful handover procedure inaccordance with an embodiment of the present disclosure;

FIG. 6 shows a diagram 600 of a handover failure procedure in accordancewith an embodiment of the present disclosure;

FIG. 7 shows a block diagram of a terminal device 700 in accordance withan embodiment of the present disclosure;

FIG. 8 shows a block diagram of a network device 800 in accordance withan embodiment of the present disclosure; and

FIG. 9 shows a simplified block diagram 900 of a device that is suitablefor use in implementing embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure will now be discussed with reference to severalexample embodiments. It should be understood that these embodiments arediscussed only for the purpose of enabling those skilled persons in theart to better understand and thus implement the present disclosure,rather than suggesting any limitations on the scope of the presentdisclosure.

As used herein, the term “wireless communication network” refers to anetwork following any suitable communication standards, such asLTE-Advanced (LTE-A), LTE, Wideband Code Division Multiple Access(WCDMA), High-Speed Packet Access (HSPA), and so on. Furthermore, thecommunications between a terminal device and a network device in thewireless communication network may be performed according to anysuitable generation communication protocols, including, but not limitedto, the first generation (1G), the second generation (2G), 2.5G, 2.75G,the third generation (3G), the fourth generation (4G), 4.5G, the futurefifth generation (5G) communication protocols, and/or any otherprotocols either currently known or to be developed in the future.

The term “network device” refers to a base station (BS), an access point(AP), a mobile management entity, a server, and any other suitabledevice in the wireless communication network. The network device may be,for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), aRemote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH),a relay, a low power node such as a femto, a pico, and so forth.

The term “terminal device” refers to user equipment (UE), which may be aSubscriber Station (SS), a Portable Subscriber Station, a Mobile Station(MS), or an Access Terminal (AT). The terminal device may include, butnot limited to, a mobile phone, a cellular phone, a smart phone, atablet, a wearable device, a personal digital assistant (PDA), and thelike.

As used herein, the terms “first” and “second” refer to differentelements. The singular forms “a” and “an” are intended to include theplural forms as well, unless the context clearly indicates otherwise.The terms “comprises,” “comprising,” “has,” “having,” “includes” and/or“including” as used herein, specify the presence of stated features,elements, and/or components and the like, but do not preclude thepresence or addition of one or more other features, elements, componentsand/or combinations thereof. The term “based on” is to be read as “basedat least in part on.” The term “one embodiment” and “an embodiment” areto be read as “at least one embodiment.” The term “another embodiment”is to be read as “at least one other embodiment.” Other definitions,explicit and implicit, may be included below.

Now some exemplary embodiments of the present disclosure will bedescribed below with reference to the figures. Reference is first madeto FIG. 1, which illustrates an environment of a wireless communicationnetwork 100 in which embodiments of the present disclosure may beimplemented. As shown in FIG. 1, the wireless communication network 100is illustrated as a LTE network in which D2D communication is performedbetween terminal devices. In particular, a network device 110 (alsoreferred to as a “BS 110” hereafter) manages a serving cell 160 thatserves three terminal devices 120, 130 and 150 in the LTE network, andthe terminal devices 120, 130 and 140 perform D2D communication or V2Xcommunication.

It is to be understood that the configuration of FIG. 1 is describedmerely for the purpose of illustration, without suggesting anylimitation as to the scope of the present disclosure. Those skilled inthe art will appreciate that the wireless communication network 100 mayinclude any suitable number of terminal devices and BSs and may haveother suitable configurations.

Conventionally, several phases may be involved in the handover of theterminal device 120 from the serving cell (also referred to as “sourcecell” hereafter) to a new cell (also referred to as “target cell”hereafter). FIG. 2 shows a diagram of flow 200 of a handover procedure.In FIG. 2, UE indicates the terminal device 120, S-eNB (also referred toas the “source eNB” hereafter) indicates the network device 110 or thesource BS, and the T-eNB (also referred to as the “target eNB”hereafter) indicates a target BS that manages the target cell of thehandover. Four phases are illustrated in the example of FIG. 2 asfollows:

1. Normal Phase: During this phase, UE is connected to source eNB andcan transmit V2X data using either mode1 resources or mode2 resources.Phase 1 starts with sending 201 a handover request from the S-eNB to theT-eNB. Then the T-eNB sends 202 a handover request acknowledgment (ACK)to the S-eNB. Phase 1 finishes when UE receives 203, from the S-eNB,RRCConnectionReconfiguration including mobility information.

2. Detach Phase: This phase starts from UE detaching 204 from the S-eNBto UE being connected to the T-eNB (step 207). In particular, afterdetaching from the S-eNB, the UE sends 205 a message for synchronizationto the T-eNB. Upon receiving the synchronization message, the T-eNBsends 206 uplink (UL) resource and Timing Advance (TA) to the UE. Then,the UE sends 207 RRCConnectionRegonfigurationComplete to the T-eNB.During this phase, UE is not connected to any eNB.

3. Abnormal phase: During this phase, UE is connected to the target BS,but cannot use the resources from target BS for V2X transmission.

If UE is going to use mode2 resource, abnormal phase will be from step207 to step 208 where V2X System Information Block (SIB) is receivedfrom the T-eNB. During this phase, UE is connected to the target BS, butcannot use mode2 resources to perform V2X transmission, as V2X mode2resource pool is not obtained by UE.

If UE is going to use mode1 resource, abnormal phase will be from step207 to step 210. (In ProSe, SidelinkUEInformation was defined for UE toobtain necessary information from eNB for mode1 resource allocation. Itis assumed this message will be reused by V2X). In this phase, afterreceiving 208 V2X SIB from the T-eNB, the UE sends 209SidelinkUEInformation to the T-eNB, and then receives 210RRCConnectionReconfiguration from the T-eNB. During this phase, UE isconnected to target eNB, but cannot use mode1 resources to perform V2Xtransmission, as some necessary information of mode1 resource allocationis still missing from UE side.

4. Normal phase: UE is connected to target eNB and can use resourcesfrom target eNB to transmit V2X data. If UE is going to use mode2resource, this phase starts from step 208. If UE is going to use mode1resources, this phase starts from step 210.

However, during “2 Detach phase”, UE cannot obtain resources for V2Xtransmission, neither from the source BS nor from the target BS. At thesame time, UE is under network coverage, it cannot use pre-configuredresources as what a UE out of coverage will use. As a result, there willbe service interruption during this phase, and the interruption time canbe up to 2 seconds, which will be unacceptable for some V2X services.

Recently, studies have been made for addressing this problem. Onesolution (also referred to as “solution #1”) is to use the resources ofthe source eNB, i.e. UE will continue using resources of source eNBafter detached from source eNB. However, there are quite a fewdrawbacks.

First, there is interference to target eNB. During this phase, the UEmay have been in the coverage of target eNB, e.g. when UE performs step5, 6 and 7. The V2X resource pool can be not aligned between source eNBand target eNB. The V2X resources in source eNB can be used to scheduleLTE traffic in target eNB. As a result, UE using the resources of sourceeNB may lead to interference to target eNB. Considering the duration ofthis phase can be up to 2 seconds, the impact can be critical.

Second, resources may be wasted. During this phase, the UE isunconnected to source eNB, i.e. source eNB has no idea about when thisphase will stop. eNB has to reserve the resources for the UE minimum 2seconds to make it work for all cases. When this phase is short, e.g.tens of ms, some resources will be waste.

Another solution (also referred to as “solution #2”) is to use theresources of target eNB. That is, the target eNB can provide someresources to UE via Handover Command message, and UE can use theseresources during “2 Detach phase”. There are similar drawbacks withsolution #1.

In order to solve the above and other potential problems, embodiments ofthe present disclosure provide solutions on resource configurationduring the handover. FIG. 3 shows a flowchart of a method 300 forresource configuration implemented by a terminal device in accordancewith an embodiment of the present disclosure. With the method 300, theabove and other potential deficiencies in the conventional approachescan be overcome. It would be appreciated by those skilled in the artthat the method 300 may be implemented by a terminal device, such as theterminal device 120 or other suitable devices. For the purpose ofillustration, the method 300 will be described below with reference tothe terminal device 120 in the wireless communication system 100.

The method 300 is entered in block 310, where information aboutsupplemental resource is received from a source cell. The supplementalresource refers to the resource available to the terminal device duringat least a portion of a transition period of the handover. Thetransition period indicates a period of time for performing thehandover, for example, from the time point of receiving 203 theRRCConnectionReconfiguration message from the source cell to the timepoint of receiving 210 the RRCConnectionReconfiguration message from thetarget cell, as shown in the example of FIG. 2. In some embodiments ofthe present disclosure, the supplemental resource is pre-configured orconfigured by the serving cell of the terminal device before handover.The supplemental resource takes effect according to a specific timerand/or a specific event during the handover. The timing of thesupplemental resource may follow Global Navigation Satellite System(GNSS) timing reference or a common timing reference (if universaltiming in the system) or target cell timing (if different timing in thesystem). The supplemental resource cannot be used by LTE traffic inserving/target cell for interference avoidance.

In some embodiments, the supplemental resource may be implemented as aresource pool which includes one or more time/frequency resource blocks,for example, Physical Resource Blocks (PRBs). The supplemental resourcemay be notified by the source cell, for example, in a HO command(dedicated RRC signaling), SIB (broadcast RRC signaling), or the like.

In block 320, a time interval is determined in a transition period of ahandover from the source cell to a target cell based on a timerassociated with a random access procedure in the handover. The timer mayhave different states, such as a stopping state, an expiring state, andso on. If the timer is stopped, namely, the timer enters a stoppingstate, it can be determined that the random access procedure issuccessful. If the timer expires, namely, the timer enters an expiringstate, it can be determined that the random access procedure is failed.In some embodiments, the timer may be T304 or other suitable timer thathas been already defined.

The time interval refers to a portion of the transition period in whichthe supplemental resource is available to the terminal device. Accordingto embodiments of the present disclosure, there may be a variety of waysto determine the time interval.

In some embodiments, a time point when the timer is started may bedetermined as a beginning of the time interval, and an end of the timeinterval may be determined based on a state of the timer. FIG. 5 shows adiagram 500 of a successful handover procedure in accordance with anembodiment of the present disclosure. In the example of FIG. 5, thebeginning of the time interval may be the time point 501 at which thetimer T304 is started, and the transition period is indicated by 510. Insome embodiments, the time point 501 may correspond to a time point atwhich a RRCConnectionReconfiguration message is received from the sourcecell. FIG. 6 shows a diagram 600 of a handover failure procedure inaccordance with an embodiment of the present disclosure. In the exampleof FIG. 6, the beginning of the time interval may be the time point 601at which the timer T304 is started, and the transition period isindicated by 610 which starts from the time point 601 to the time point603. The time point 603 indicates a time point at which a new cell isselected. In an alternative embodiment, the transition period 610 maystart from the time point 601 and ends at the time point 602. The timepoint 602 indicates a time point at which the timer T304 expires.

The end of the time interval may be determined based on the state of thetimer in multiple ways. In an embodiment, in response to the timer beingstopped before expiring, a time point when the timer is stopped may bedetermined as the end of the time interval. In the example of FIG. 5,the end of the time interval may be the time point 502 at which thetimer T304 is stopped when the random access procedure is successfullycompleted.

Alternatively, in an embodiment, in response to the timer being stoppedbefore expiring, a time point when RRC connection reconfiguration isreceived may be determined as the end of the time interval. In theexample of FIG. 5, the end of the time interval may be the time point503 at which the RRCConnectionReconfiguration message is received.

Alternatively, in an embodiment, in response to the timer expiring, atime point when the timer expires may be determined as the end of thetime interval. In the example of FIG. 6, the end of the time intervalmay be the time point 602 at which the timer T304 expires.

Alternatively, in an embodiment, in response to the timer expiring, atime point when a further timer associated with a cell selectionprocedure is stopped or expires may be determined as the end of the timeinterval. The further timer may be T311. The cell selection proceduremay be performed after the random access procedure. In the example ofFIG. 6, the end of the time interval may be the time point 603 at whichthe timer T311 is stopped when a suitable E-UTRA cell is selected.

As an alternative, the beginning of the time interval may be not thesame as the starting time of the timer. In some embodiments, in responseto the timer being stopped before expiring, a time point when the timeris stopped may be determined as a beginning of the time interval. Inthis case, a time point when RRC connection reconfiguration is receivedmay be determined as an end of the time interval. In the example of FIG.5, the beginning of the time interval may be the time point 502 when thetimer T304 is stopped, and the end of the time interval may be the timepoint 503 at which a RRCConnectionReconfiguration message is received.

According to embodiments of the present disclosure, optionally, thetimer may be adjusted according to GNSS timing, common timing of thewireless communication network, and/or the like. The common timing maybe, for example, a universal timing in the wireless communicationnetwork, or a timing commonly used by both the target cell and thesource cell. In embodiments where the timer is stopped before expiring,that is, the random access procedure is successful, the timer may beadjusted according to the GNSS timing, the common timing of the wirelesscommunication network, timing of the target cell (if there are differenttimings in the wireless communication network), and/or the like.

As discussed above, according to embodiments of the present disclosure,the supplemental resource can be available to the terminal device duringthe time interval in the transition period of the handover. In this way,the V2X communication can be not affected by the handover. In addition,using the supplemental resource during handover can avoid theinterference to the LTE traffic in neighboring cells or the cells inproximity. Furthermore, overlapping the supplemental resource withordinary V2X resources can improve resource utilization.

Reference is now made to FIG. 4, which shows a flowchart of a method 400for resource configuration implemented by a network device in accordancewith an embodiment of the present disclosure. It would be appreciated bythose skilled in the art that the method 400 may be implemented by anetwork device, such as the BS 110 or other suitable devices. For thepurpose of illustration, the method 400 will be described below withreference to the BS 110 in the wireless communication system 100.

The method 400 is entered in block 410, where information aboutsupplemental resource is transmitted to a terminal device, to enable theterminal device to determine, based on a timer associated with a randomaccess procedure in a handover of the terminal device, a time intervalin a transition period of the handover. The supplemental resource isavailable to the terminal device in the determined time interval.

According to embodiments of the present disclosure, the supplementalresource may be implemented as a resource pool which includes one ormore time/frequency resource blocks, for example, PRBs. The supplementalresource may be pre-configured or configured by the serving cell beforehandover. In some embodiments, the supplemental resource may be notifiedby the source cell to the terminal device, for example, in a HO command(dedicated RRC signaling), SIB (broadcast RRC signaling), or the like.

Upon receipt of the information of the supplemental resource, theterminal device, for example, the terminal device 120 of FIG. 1, mayperform the method 300 to determine the time interval in which thesupplemental resource is available for use.

Now more details of some embodiments will be described with respect toFIGS. 5 and 6.

Embodiment 1: Supplemental Resource is to be Used Based on a TimerDuring the Transition Period

As shown in FIG. 5, conventionally, if HO is successful, the resourceconfiguration of serving cell would be released since HO command isreceived from source cell, and the resource configuration of target cellwould be obtained after RRCConnectionReconfiguration from target cell,i.e., no clear resource definition during the transition period. In theexample of FIG. 6, if HO fails, there is no resource available as wellat least during T304 time period, no matter whether RRC connectionre-establishment is successful or not.

According to embodiments of the present disclosure, in embodiment 1, theresource usage may include the following steps.

Step 1: the supplemental resource (time/frequency domain definition,limited one time/frequency resource or resource set/pool) is notified bythe source cell, either in HO command (dedicated RRC signaling) or SIB(broadcast RRC signaling).

Step 2: the resource is to be used by the UE since T304 is started,referring to a universal timing (either GNSS or a common timing used bywhole system). There may be multiple cases where the usage of theresource would be stopped:

-   -   Stopped when the MAC layer has successfully done the random        access procedure;    -   Stopped when the RRC connection reconfiguration is received from        the target cell;    -   Stopped when T304 expires; or    -   Stopped when T311 stops/expires (in this case, the supplemental        resource may be continued to be used when T304 expires).

Step 3: afterwards, new resource may be available. In some embodiments,the new resource may be implemented as resource configured by targetcell (carried in RRC connection reconfiguration, or SIB in target cell,or the like). In some alternative embodiments, the new resource may beconfigured for out of coverage case, if HO fails as described in FIG. 6.In the example of FIG. 6, the new resource (for example, an exceptionalresource pool or preconfigured resource) may be available after the timepoint 603, and may be associated with a new timer, for example, T301. Inanother example where the transition period starting from the time point601 and ending at the time point 602, the exceptional resource pool maybe available after the time point 602.

Embodiment 2: Supplemental Resource is to be Used Based on an EventAssociated with the Timer During the Transition Period

As shown in FIG. 6, the timer T304 started after HO command may be seenas an uncertain period. For example, it may either end with HO failure(no matter RRC connection re-establishment is successful or not) or HOsuccess. So if considering the resources can be configured from targetcell perspective, and different timing is used by different eNBs, thisresource would be used after successful connection with target cell.

So in this embodiment, the resource usage may include the followingsteps.

Step 1: the supplemental resource (time/frequency domain definition,limited one t/f resource or resource set/pool) is notified by sourcecell, either in HO command (dedicated RRC signaling) or SIB (broadcastRRC signaling).

Step 2: the supplemental resource is to be used by the UE since randomaccess is successful at MAC layer, referring to the timing of a targetcell.

Step 3: the supplemental resource may be stopped when RRC connectionreconfiguration is received, where new resource configuration isincluded.

FIG. 7 shows a block diagram of a terminal device 700 in accordance withan embodiment of the present disclosure. It would be appreciated thatthe terminal device 700 may be implemented by the terminal device 120 asshown in FIG. 1 or other suitable devices.

As shown, the terminal device 700 includes a receiver 710 and acontroller 720. The receiver 710 is configured to receive informationabout supplemental resource from a source cell. The controller 720configured to determine, based on a timer associated with a randomaccess procedure in a handover from the source cell to a target cell, atime interval in a transition period of the handover, the supplementalresource being available to the terminal device in the determined timeinterval.

In an embodiment, the controller 720 is further configured to: determinea time point when the timer is started as a beginning of the timeinterval; and determine an end of the time interval based on a state ofthe timer.

In an embodiment, the controller 720 is further configured to: inresponse to the timer being stopped before expiring, determine a timepoint when the timer is stopped as the end of the time interval.

In an embodiment, the controller 720 is further configured to: inresponse to the timer being stopped before expiring, determine a timepoint when RRC connection reconfiguration is received as the end of thetime interval.

In an embodiment, the controller 720 is further configured to: inresponse to the timer expiring, determine a time point when the timerexpires as the end of the time interval.

In an embodiment, the controller 720 is further configured to: inresponse to the timer expiring, determine a time point when a furthertimer associated with a cell selection procedure is stopped or expiresas the end of the time interval, the cell selection procedure beingperformed after the random access procedure.

In an embodiment, the controller 720 is further configured to: adjustthe timer according to at least one of: GNSS timing, and common timingof the wireless communication network.

In an embodiment, the controller 720 is further configured to: inresponse to the timer being stopped before expiring, determine a timepoint when the timer is stopped as a beginning of the time interval; anddetermine a time point when RRC connection reconfiguration is receivedas an end of the time interval.

In an embodiment, the controller 720 is further configured to: adjustthe timer according to at least one of: GNSS timing, common timing ofthe wireless communication network, and timing of the target cell.

In an embodiment, the timer may be T304.

FIG. 8 shows a block diagram of a network device 800 in accordance withan embodiment of the present disclosure. It would be appreciated thatthe network device 800 may be implemented by the BS 110 as shown in FIG.1 or other suitable devices.

As shown, the network device 800 includes a transmitter 810 configuredto transmit information about supplemental resource to a terminaldevice, to enable the terminal device to determine, based on a timerassociated with a random access procedure in a handover of the terminaldevice, a time interval in a transition period of the handover, thesupplemental resource being available to the terminal device in thedetermined time interval.

It should be appreciated that components included in the terminal device700 correspond to the blocks of the method 300, and components includedin the network device 800 correspond to the blocks of the method 400.Therefore, all operations and features described above with reference toFIG. 3 are likewise applicable to the components included in theterminal device 700 and have similar effects, and all operations andfeatures described above with reference to FIG. 4 are likewiseapplicable to the components included in the network device 800 and havesimilar effects. For the purpose of simplification, the details will beomitted.

The components included in the terminal device 700 and the networkdevice 800 may be implemented in various manners, including software,hardware, firmware, or any combination thereof. In one embodiment, oneor more units may be implemented using software and/or firmware, forexample, machine-executable instructions stored on the storage medium.In addition to or instead of machine-executable instructions, parts orall of the components included in the terminal device 700 and thenetwork device 800 may be implemented, at least in part, by one or morehardware logic components. For example, and without limitation,illustrative types of hardware logic components that can be used includeField-programmable Gate Arrays (FPGAs), Application-specific IntegratedCircuits (ASICs), Application-specific Standard Products (ASSPs),System-on-a-chip systems (SOCs), Complex Programmable Logic Devices(CPLDs), and the like.

In accordance with embodiments of the present disclosure, there isprovided an apparatus implemented in a wireless communication network.It would be appreciated that the apparatus may be implemented at aterminal device. The apparatus includes: means for receiving informationabout supplemental resource from a source cell; and means fordetermining, based on a timer associated with a random access procedurein a handover from the source cell to a target cell, a time interval ina transition period of the handover, the supplemental resource beingavailable to the terminal device in the determined time interval.

In an embodiment, the means for determining the time interval includes:means for determining a time point when the timer is started as abeginning of the time interval; and means for determining an end of thetime interval based on a state of the timer.

In an embodiment, the means for determining the end of the time intervalincludes: means for, in response to the timer being stopped beforeexpiring, determining a time point when the timer is stopped as the endof the time interval.

In an embodiment, the means for determining the end of the time intervalincludes: means for, in response to the timer being stopped beforeexpiring, determining a time point when RRC connection reconfigurationis received as the end of the time interval.

In an embodiment, the means for determining the end of the time intervalincludes: means for, in response to the timer expiring, determining atime point when the timer expires as the end of the time interval.

In an embodiment, the means for determining the end of the time intervalincludes: means for, in response to the timer expiring, determining atime point when a further timer associated with a cell selectionprocedure is stopped or expires as the end of the time interval, thecell selection procedure being performed after the random accessprocedure.

In an embodiment, the apparatus further includes: means for adjustingthe timer according to at least one of: GNSS timing, and common timingof the wireless communication network.

In an embodiment, the means for determining the time interval includes:means for, in response to the timer being stopped before expiring,determining a time point when the timer is stopped as a beginning of thetime interval; and means for determining a time point when RRCconnection reconfiguration is received as an end of the time interval.

In an embodiment, the apparatus further includes: means for, adjustingthe timer according to at least one of: GNSS timing, common timing ofthe wireless communication network, and timing of the target cell.

In an embodiment, the timer may be T304.

In accordance with embodiments of the present disclosure, there isprovided an apparatus implemented in a wireless communication network.It would be appreciated that the apparatus may be implemented at anetwork device. The apparatus includes: means for transmittinginformation about supplemental resource to a terminal device, to enablethe terminal device to determine, based on a timer associated with arandom access procedure in a handover of the terminal device, a timeinterval in a transition period of the handover, the supplementalresource being available to the terminal device in the determined timeinterval.

FIG. 9 shows a simplified block diagram of a device 900 that is suitablefor use in implementing embodiments of the present disclosure. It wouldbe appreciated that the device 900 may be implemented by a networkdevice, such as, the BS 110, or a terminal device, for example theterminal device 120.

As shown, the device 900 includes a data processor (DP) 910, a memory(MEM) 920 coupled to the DP 910, a suitable RF transmitter TX andreceiver RX 940 coupled to the DP 910, and a communication interface 950coupled to the DP 910. The MEM 920 stores a program (PROG) 930. TheTX/RX 940 is for bidirectional wireless communications. Note that theTX/RX 940 has at least one antenna to facilitate communication, thoughin practice an Access Node mentioned in this application may haveseveral ones. The communication interface 950 may represent anyinterface that is necessary for communication with other networkelements, such as X2 interface for bidirectional communications betweeneNBs, S1 interface for communication between a Mobility ManagementEntity (MME)/Serving Gateway (S-GW) and the eNB, Un interface forcommunication between the eNB and a relay node (RN), or Uu interface forcommunication between the eNB and a terminal device.

The PROG 930 is assumed to include program instructions that, whenexecuted by the associated DP 910, enable the device 900 to operate inaccordance with the embodiments of the present disclosure, as discussedherein with the method 300 in FIG. 3 or the method 400 in FIG. 4. Theembodiments herein may be implemented by computer software executable bythe DP 910 of the device 900, or by hardware, or by a combination ofsoftware and hardware. A combination of the data processor 910 and MEM920 may form processing means 960 adapted to implement variousembodiments of the present disclosure.

The MEM 920 may be of any type suitable to the local technicalenvironment and may be implemented using any suitable data storagetechnology, such as semiconductor based memory devices, magnetic memorydevices and systems, optical memory devices and systems, fixed memoryand removable memory, as non-limiting examples. While only one MEM isshown in the device 900, there may be several physically distinct memorymodules in the device 900. The DP 910 may be of any type suitable to thelocal technical environment, and may include one or more of generalpurpose computers, special purpose computers, microprocessors, digitalsignal processors (DSPs) and processors based on multicore processorarchitecture, as non-limiting examples. The device 900 may have multipleprocessors, such as an application specific integrated circuit chip thatis slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may beimplemented in hardware or special purpose circuits, software, logic orany combination thereof. Some aspects may be implemented in hardware,while other aspects may be implemented in firmware or software which maybe executed by a controller, microprocessor or other computing device.While various aspects of embodiments of the present disclosure areillustrated and described as block diagrams, flowcharts, or using someother pictorial representation, it will be appreciated that the blocks,apparatus, systems, techniques or methods described herein may beimplemented in, as non-limiting examples, hardware, software, firmware,special purpose circuits or logic, general purpose hardware orcontroller or other computing devices, or some combination thereof.

By way of example, embodiments of the present disclosure can bedescribed in the general context of machine-executable instructions,such as those included in program modules, being executed in a device ona target real or virtual processor. Generally, program modules includeroutines, programs, libraries, objects, classes, components, datastructures, or the like that perform particular tasks or implementparticular abstract data types. The functionality of the program modulesmay be combined or split between program modules as desired in variousembodiments. Machine-executable instructions for program modules may beexecuted within a local or distributed device. In a distributed device,program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may bewritten in any combination of one or more programming languages. Theseprogram codes may be provided to a processor or controller of a generalpurpose computer, special purpose computer, or other programmable dataprocessing apparatus, such that the program codes, when executed by theprocessor or controller, cause the functions/operations specified in theflowcharts and/or block diagrams to be implemented. The program code mayexecute entirely on a machine, partly on the machine, as a stand-alonesoftware package, partly on the machine and partly on a remote machineor entirely on the remote machine or server.

In the context of this disclosure, a machine readable medium may be anytangible medium that may contain, or store a program for use by or inconnection with an instruction execution system, apparatus, or device.The machine readable medium may be a machine readable signal medium or amachine readable storage medium. A machine readable medium may includebut not limited to an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples of the machinereadable storage medium would include an electrical connection havingone or more wires, a portable computer diskette, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CD-ROM), an optical storage device, amagnetic storage device, or any suitable combination of the foregoing.

In the context of this disclosure, the device may be implemented in thegeneral context of computer system-executable instructions, such asprogram modules, being executed by a computer system. Generally, programmodules may include routines, programs, objects, components, logic, datastructures, and so on that perform particular tasks or implementparticular abstract data types. The device may be practiced indistributed cloud computing environments where tasks are performed byremote processing devices that are linked through a communicationsnetwork. In a distributed cloud computing environment, program modulesmay be located in both local and remote computer system storage mediaincluding memory storage devices.

Further, while operations are depicted in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results. Incertain circumstances, multitasking and parallel processing may beadvantageous. Likewise, while several specific implementation detailsare contained in the above discussions, these should not be construed aslimitations on the scope of the present disclosure, but rather asdescriptions of features that may be specific to particular embodiments.Certain features that are described in the context of separateembodiments may also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment may also be implemented in multipleembodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specificto structural features and/or methodological acts, it is to beunderstood that the present disclosure defined in the appended claims isnot necessarily limited to the specific features or acts describedabove. Rather, the specific features and acts described above aredisclosed as example forms of implementing the claims.

What is claimed is:
 1. A method implemented at a terminal device for usein a wireless communication network, comprising: receiving informationabout a supplemental resource from a source cell of the wirelesscommunication network; and determining a time interval in a portion of atransition period of a handover of the terminal device from the sourcecell to a target cell, in which the supplemental resource is availableto the terminal device during the time interval, wherein a first timerand the time interval commence at a receiving of a connectionreconfiguration message from the source cell, wherein when the firsttimer expires without the terminal device completing target cellselection, utilizing a second timer to add time to the first timer tocontinue the time interval for target cell selection, and wherein thetime interval ends upon successful target cell selection or upon expiryof the second timer.
 2. The method of claim 1, wherein the supplementalresource is for use in device-to-device communication during handover ofthe terminal device from the source cell to the target cell.
 3. Themethod of claim 2, wherein the first timer is T304.
 4. The method ofclaim 3, wherein the second timer is T311.
 5. The method of claim 2further comprising determining a second time interval commencing uponunsuccessful target cell selection at the expiry of the second timer, inwhich a new resource for use in device-to-device communication is madeavailable to the terminal device, wherein the second time intervalexpires upon expiry of a third timer.
 6. The method of claim 5, whereinthe third timer is T301.
 7. The method of claim 5, wherein the firsttimer is T302, the second timer is T311, and the third timer is T301. 8.The method of claim 5, further comprising receiving information aboutthe new resource from the target cell of the wireless communicationnetwork.
 9. An apparatus implemented at a terminal device for use in awireless communication network, comprising: a receiver configured toreceive information about a supplemental resource from a source cell ofthe wireless communication network; and a controller configured todetermine a time interval in a portion of a transition period of ahandover of the terminal device from the source cell to a target cell,in which the supplemental resource is available to the terminal deviceduring the time interval, wherein a first timer and the time intervalcommence at a receiving of a connection reconfiguration message from thesource cell, wherein when the first timer expires without the terminaldevice completing target cell selection, utilize a second timer to addtime to the first timer to continue the time interval for target cellselection, and wherein the time interval ends upon successful targetcell selection or upon expiry of the second timer.
 10. The apparatus ofclaim 9, wherein the supplemental resource is for use indevice-to-device communication during handover of the terminal devicefrom the source cell to the target cell.
 11. The apparatus of claim 10,wherein the first timer is T304 and the second timer is T311.
 12. Theapparatus of claim 10, wherein the receiver further determines a secondtime interval commencing upon unsuccessful target cell selection at theexpiry of the second timer, in which a new resource for use indevice-to-device communication is made available to the terminal device,wherein the second time interval expires upon expiry of a third timer.13. The apparatus of claim 12, wherein the first timer is T302, thesecond timer is T311, and the third timer is T301.
 14. The apparatus ofclaim 12, wherein the controller further receives information about thenew resource from the target cell of the wireless communication network.15. A method implemented at a network device in a wireless communicationnetwork, comprising: preparing for transmission to a terminal device,information about a supplemental resource for use by the terminal deviceduring a handover of the terminal device from a source cell to a targetcell, the information including a time interval in a portion of atransition period of the handover, in which the supplemental resource isavailable to the terminal device during the time interval, wherein afirst timer and the time interval commence at a receiving of aconnection reconfiguration message from the source cell by the terminaldevice, wherein when the first timer expires without the terminal devicecompleting target cell selection, utilizing a second timer to add timeto the first timer to continue the time interval for target cellselection at the terminal device, and wherein the time interval endsupon successful target cell selection by the terminal device or uponexpiry of the second timer; and sending the information to the terminaldevice by the source cell.
 16. The method of claim 15 further comprisingsending information about a second time interval to commence uponunsuccessful target cell selection by the terminal device at the expiryof the second timer, in which a new resource for use in device-to-devicecommunication is made available to the terminal device, wherein thesecond time interval expires upon expiry of a third timer.
 17. Themethod of claim 16, wherein the first timer is T302, the second timer isT311, and the third timer is T301.
 18. An apparatus implemented at anetwork device in a wireless communication network, comprising: acontroller configured to cause a transmission of information to aterminal device, the information about a supplemental resource for useby the terminal device during a handover of the terminal device from asource cell to a target cell, the information including a time intervalin a portion of a transition period of the handover, in which thesupplemental resource is available to the terminal device during thetime interval, wherein a first timer and the time interval commence at areceiving of a connection reconfiguration message from the source cellby the terminal device, wherein when the first timer expires without theterminal device completing target cell selection, utilizing a secondtimer to add time to the first timer to continue the time interval fortarget cell selection at the terminal device, and wherein the timeinterval ends upon successful target cell selection by the terminaldevice or upon expiry of the second timer.
 19. The apparatus of claim18, wherein the controller further causes a transmission of informationabout a second time interval commencing upon unsuccessful target cellselection by the terminal device at the expiry of the second timer, inwhich a new resource for use in device-to-device communication is madeavailable to the terminal device, wherein the second time intervalexpires upon expiry of a third timer.
 20. The apparatus of claim 19,wherein the first timer is T302, the second timer is T311, and the thirdtimer is T301.